Directional video filters for locally adaptive spatial noise reduction
First Claim
1. A method of reducing spatial noise in an image having a plurality of pixels, comprising:
- detecting object boundaries and unstructured areas in the image by applying 3-tap high pass filters to each pixel in the image in at least four directions to determine the best direction(s) for local low pass filtering; and
applying low pass filtering only along object boundaries and unstructured areas within the image so as to minimize the tendency to blur image edges.
4 Assignments
0 Petitions
Accused Products
Abstract
Spatial noise is reduced in an image having a plurality of pixels by detecting object boundaries and unstructured areas in the image and applying 3-tap high pass filters to each pixel in the image in at least four, but less than eight directions to determine the best direction for local low pass filtering. Low pass filtering is applied only along object boundaries and unstructured areas within the image so as to minimize the tendency to blur image edges. Using only four high pass filters to locate horizontal, vertical and diagonal image edges passing through the center of a 3×3 pixel array provides good results.
-
Citations
25 Claims
-
1. A method of reducing spatial noise in an image having a plurality of pixels, comprising:
-
detecting object boundaries and unstructured areas in the image by applying 3-tap high pass filters to each pixel in the image in at least four directions to determine the best direction(s) for local low pass filtering; and
applying low pass filtering only along object boundaries and unstructured areas within the image so as to minimize the tendency to blur image edges. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
-
-
14. A method of performing directional smoothing of an image, comprising:
-
for each pixel p(i,j) in a video frame of I rows by J columns, computing a set of zero-mean high-pass filters with tap weights, where the center tap coefficient is twice that of the taps applied to the neighboring pixels which have an opposite sign, for only the horizontal, vertical, and two diagonal directions; and
applying low pass filtering only along object boundaries and unstructured areas within the image so as to minimize the tendency to blur image edges. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23)
-
-
24. A method of performing spatial noise filtering of an image, comprising:
-
applying a plurality of 3-tap zero-mean high pass filters to determine a plurality of low pass filter shapes, varying the relative weight of the center tap of the high pass filters in the range of unity down to zero. - View Dependent Claims (25)
-
Specification